On the determination of the diffusion constants of H$_{2}$O, phenyls, ZRh$_{1,26}$, and D$_{2}$O by neutron single scattering experiments : Preprint

Springer, T.; Hofmeyr, C.; Kornbichler, S.; Lemmel, H. D.

Book/Report

FZJ-2017-02513

On the determination of the diffusion constants of H$_{2}$O, phenyls, ZRh$_{1,26}$, and D$_{2}$O by neutron single scattering experiments : Preprint

Springer, T.FZJ* ; Hofmeyr, C. ; Kornbichler, S. ; Lemmel, H. D.

1964
Kernforschungsanlage Jülich, Verlag Jülich

Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 160, 15 p. (1964)

Please use a persistent id in citations: http://hdl.handle.net/2128/14076

Report No.: Juel-0160-NP

Abstract: The average thermal diffusion constant <Dv> is usually determined by integral methods, i.e. by investigating the relaxation of the neutron density in time or in space. In this paper a different approach is described. From measurements of the differential sca ttering cross-section dE ($\theta$) /d$\Omega$ for various neutron energies E and sample temperatures T$_{m}$, the average cosine of the scattering angle $\overline{\mu}$, the diffusion constant D(E,T$_{m}$), and its thermal average <Dv>$_{Tm}$ was calculated. Investigations were performed on the most important hydrogeneous moderators and on D$_{2}$O. It was found that the scattering cross sections d5/d$\Omega$, are not very sensitive to the temperature. Therefore, the quantity <Dv> can easily be evaluated within a large temperature range by means of a comparatively small number of d5/d$\Omega$ -measurements. A qualitative explanation of the very streng interference maxima in the d5/d$\Omega$, -curves of D$_{2}$O can be given. Rather strong coherence maxima have been observed in the phenyl-and ZrH-curves, too. Very good agreement was obtained between our <Dv>-data and the results of conventional relaxation experiments both with light and heavy water. There was also good agreement with theoretical predictions for H$_{2}$O, D$_{2}$O, diphenyl, and reasonable agreement with calculations for ZrH$_{1,26}$. For diphenyl, there was agreement with some of the relaxation experiments cited in literature. The consistency of the results shows that our thermal diffusion parameters <Dv>as a function of T$_{m}$ and the diffusion constant D as a function of E can be considered as reliable for one-or multigroup-calculations.

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